The present invention relates to an apparatus for texturing a synthetic yarn.
Yarn nozzles are known from German DE-C 36 34 749 and corresponding to U.S. Pat. No. 4,796,340 and wherein the yarn nozzle is provided with a yarn duct which is supplied with hot air and terminates in an expansion chamber which has a larger cross section than the yarn duct. The expansion chamber possesses lateral outlets, for example axially extending slots, and is therefore connected with the atmosphere. The hot air which is supplied into the yarn duct expands with the yarn in the expansion chamber. Consequently, the multifilament yarn is expanded in the expansion chamber and compressed to a yarn plug thereby being deformed. This yarn plug is further advanced by the pressure in the expansion chamber, then deposited after leaving the expansion chamber on a slowly rotating cooling drum, and finally disentangled to a crimped yarn, note also DE-C 26 32 082 and corresponding to U.S. Pat. No. 4,118,843.
In the above nozzles, the hot air is generated in a heater. To regulate the process, the temperature of the hot air is measured in the supply line to the nozzle, and as a function of this measured value and a desired temperature, the regulator for the heater is controlled such that the temperature remains constant.
It has been found that in the above described method, the point of disentanglement at which the yarn plug unravels again to a textured yarn, may move along the cooling drum, without it being possible to notice and detect the process parameters which cause this instability.
It is accordingly an object of the present invention to provide a yarn nozzle of the described type and wherein a stability of the texturing process is ensured, in particular that the point of disentanglement is prevented from shifting.
It is also an object of the present invention to provide a yarn nozzle of the described type and which comprises two sections which are separated or opened to facilitate yarn thread-up, and wherein large fluctuations of the output of the heater are avoided when the nozzle is opened, and so that the temperature in the air supply line to the nozzle can be maintained relatively constant during opening.